Update: Third-Round Knockouts for Auto X Prize Race

The Progressive Automotive X Prize competition wrapped up its the third and final round of dynamic knockout testing at Michigan International Speedway on Tuesday, July 27, 2010. Increasingly tough on-track efficiency targets trimmed the original field of 136 vehicles from 111 teams down to just nine entries from seven teams by the end of this last round.

As teams were knocked out left and right during round three of the Progressive Automotive X Prize fuel-efficiency testing, race director Bob Larsen remained optimistic. The minimum target for the X Prize is the equivalent of 100 mpg, but "we're seeing efficiency way, way over that," Larsen says. "Some teams are hitting 150 mpg with vehicles that are passing all the dynamic testing. The performance we're seeing here is really impressive."

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Walking through the MIS paddocks and garages on a hot and sticky July afternoon, the feeling isn't that different from any amateur race weekend. Some teams have a collegiate aura while others seem to run more like Audi's Le Mans effort. It's easy to identify the well-funded entrants. College teams can't afford scores of seasoned engineers and programmers all adorned in matching polo shirts like those from Edison or Tata. Regardless, the competition ended for vehicles on all sides, irrespective of their development and staffing budgets.

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The third round increased the efficiency threshold to a 90-mpg equivalent (mpge), up from 67 mpge. That more aggressive threshold helped bump another six vehicles out of the competition. Efficiency testing included three driving loops that approximated neighborhood, urban and highway driving styles.

The 90-degree temperatures and high humidity didn't do the contestants any favors. Another round of acceleration, braking and emergency-lane-change maneuvers tested vehicle robustness and the depth of some teams.

The nine vehicles met the 90-mpg target and survived the dynamic testing. As of press time, they were participating in coast-down exercises at MIS that would reveal more about each vehicle's rolling resistance and aerodynamic drag.

The winning teams who made it through round three include, Aptera, Edison2 (two vehicles), Li-ion Motors, RaceAbout Association, TW4XP, X-Tracer Team Switzerland (two vehicles), and Zap.

Next up: Dyno testing at the Argonne National Laboratory in Chicago. Check back in to popularmechanics.com for updates.